tanX=4
(2sinX - 3cosX)除以4cosX
點計呀???
計數.....
2007-05-14 4:59 am
回答 (2)
2007-05-14 5:14 am
✔ 最佳答案
2sinX - 3cosX)/4cosX=2sinX/4cosX - 3cosX/4cosX
=1/2tanX - 3/4
=1/2 (4) - 3/4
=5/4
參考: me
2007-05-14 9:55 am
By a right-angle triangle,
we find that
cos x= 1/sqrt(17), sin x= 4/sqrt(17)
2sin x - 3cos x= 2[4/sqrt(17)] - 3[1/sqrt(17)] = 5/sqrt(17)
and 4cosx =4/sqrt(17)
==> (2sin x - 3cosx) / 4cosx = 5 /4
we find that
cos x= 1/sqrt(17), sin x= 4/sqrt(17)
2sin x - 3cos x= 2[4/sqrt(17)] - 3[1/sqrt(17)] = 5/sqrt(17)
and 4cosx =4/sqrt(17)
==> (2sin x - 3cosx) / 4cosx = 5 /4
收錄日期: 2021-04-12 19:38:15
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20070513000051KK04798